In three minutes, estimated duration of the earthquake, the crust broke about 500 km long and 150 km wide. The many GPS stations have constituted a map of ground motions: the east coast of the island slipped four meters while the West has moved only a few tens of centimeters
The earthquake was followed by strong aftershocks, including one of magnitude 7 occurring just forty minutes after the main event and 16 above magnitude 6.
The tsunami caused by the earthquake first hit the Japanese coast before spreading across the Pacific. The wave reached a height of 30 meters in some places and penetrated up to ten miles inland, crippling the Fukushima nuclear facilities.